Titanium silical TS-1 and a method for synthesizing the same

Abstract

The application discloses a titanium silicalite TS-1 and a synthesis method thereof. The method comprises the following steps: mixing a silicon source, a quaternary ammonium base template agent and water to obtain a mixture A, and obtaining a crystal blank solution I after crystallization I, wherein the solid has an amorphous structure; mixing the silicon source, an alkali source R, water, a titanium source and a protective agent S to obtain a mixture II; mixing the crystal blank solution I and the mixture II to obtain a mixture III, and obtaining the titanium silicalite TS-1 after crystallization II. The method uses a small amount of micropore template agent in the process of synthesizing a silicon-based crystal embryo solution, does not need to add a mesopore or macropore pore-forming agent, and the amount of the micropore template agent is only 1 / 10-1 / 20 of that of a conventional method, so that the problems of high cost of the molecular sieve, environmental pollution and the like caused by high price and high toxicity of the small-molecule micropore organic template agent and the mesopore / macropore pore-forming agent are solved; meanwhile, the product has high skeleton Ti content and does not contain non-skeleton Ti and TiO2 species.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of molecular sieve, and particularly relates to a titanium silicate molecular sieve TS-1 and a synthesis method thereof. BACKGROUND

[0002] Titanium silicate zeolite (TS-1) has been synthesized since 1983, and has a wide application in the preparation of fine chemicals due to its excellent catalytic performance in a clean reaction system with hydrogen peroxide as an oxidant (such as olefin epoxidation, phenol hydroxylation, etc.). However, the synthesis cost of TS-1 zeolite is always high due to the limitation of raw materials, thereby limiting its large-scale application. On the other hand, the small pore size of the traditional TS-1 zeolite also limits its catalytic conversion of macromolecular reactants.

[0003] The main reason for the high synthesis cost of TS-1 zeolite is that a large amount of expensive organic template tetrapropylammonium hydroxide (TPAOH) and organic silicon source tetraethyl orthosilicate (TEOS) and organic titanium source tetrabutyl titanate (TBOT) need to be used in the synthesis process.

[0004] On the other hand, the prior art discloses a method for synthesizing hierarchical pore TS-1 molecular sieve by introducing a mesopore or macropore pore-forming agent in a TS-1 zeolite synthesis system, but the structure of these mesopore pore-forming agents is usually complex and the cost is high, and part of the pore-forming agents also need a complicated synthesis process to obtain, and the mesopore pore-forming agents usually need to be removed by calcination when the molecular sieve is used, which also pollutes the environment. SUMMARY

[0005] In view of this, the present application provides a titanium silicate molecular sieve TS-1 and a synthesis method thereof, and the main purpose is to solve the technical problems of high cost, complex operation and environmental unfriendliness of the synthesis method of the hierarchical pore structure of the titanium silicate molecular sieve TS-1.

[0006] In one aspect, the present application provides a synthesis method of a titanium silicate molecular sieve TS-1, which comprises the following steps:

[0007] S1: mixing raw materials containing a silicon source, a quaternary ammonium base template agent and water to obtain an initial gel mixture A, and heating and crystallizing I under a closed condition to obtain a crystal blank solution I; the solid in the crystal blank solution I has an amorphous structure;

[0008] S2: mixing raw materials containing a silicon source, an alkali source R, water, a titanium source and a protective agent S to obtain a gel mixture II;

[0009] S3: mixing the crystal seed solution I in step S1 and the gel mixture II in step S2 to obtain a gel mixture III, and crystallizing II under a closed condition to obtain the titanium silicalite TS-1.

[0010] The application provides a synthesis method of TS-1 molecular sieve with hierarchical nanoporous morphology, which can directly synthesize TS-1 molecular sieve with microporous, mesoporous and macroporous multiple structures via a high-activity crystal seed solution containing super-large specific surface area crystal seed particles under the condition of using only a small amount of microporous template agent.

[0011] Optionally, in step S1, the solid particle size in the crystal seed solution I is 10-20 nm, and the particle structure contains a five-membered ring structure.

[0012] Optionally, in step S1, the molar ratio of the silicon source, the quaternary ammonium base template agent and the water in the initial gel mixture A is:

[0013] Template agent: SiO2 = 0.10-0.50: 1;

[0014] H2O: SiO2 = 4-20: 1;

[0015] wherein the number of moles of the silicon source is calculated based on the number of moles of SiO2, the number of moles of the template agent is calculated based on the number of moles of quaternary ammonium base, and the number of moles of water is calculated based on the number of moles of H2O.

[0016] Optionally, in step S1, the molar ratio of the silicon source, the quaternary ammonium base template agent and the water in the initial gel mixture A is:

[0017] Template agent: SiO2 = 0.10-0.50: 1; preferably 0.15-0.45: 1, further preferably 0.20-0.40: 1, further preferably 0.28-0.5: 1, further preferably 0.3-0.5: 1, further preferably 0.32-0.5: 1, further preferably 0.35-0.5: 1;

[0018] H2O: SiO2 = 4-20: 1; preferably 6-18; further preferably 4-15: 1, further preferably 4-14: 1, further preferably 6-14: 1, further preferably 4-12: 1, further preferably 6-12: 1.

[0019] Optionally, in step S1, the molar ratio of template agent: SiO2 in the initial gel mixture A is selected from any value or a range value between any two values of 0.10, 0.15, 0.20, 0.25, 0.28, 0.29, 0.30, 0.31, 0.32, 0.33, 0.34, 0.35, 0.40, 0.45, 0.50.

[0020] Optionally, in step S1, the molar ratio of H2O: SiO2 in the initial gel mixture A is selected from any value or a range value between any two values of 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20.

[0021] Optionally, in step S2, the molar ratio of the silicon source, the titanium source, the alkali source R, the protective agent S and the water in the gel mixture II is:

[0022] SiO2: TiO2: R: S: H2O = 1: (0.02-0.10): (0.01-0.20): (0.04-0.2): (6-30).

[0023]

[0024] wherein the molar number of the silicon source is in terms of the molar number of SiO2, the molar number of the titanium source is in terms of the molar number of TiO2, the molar number of R is in terms of the molar number of alkali source R, the S is in terms of the molar number of protective agent S, and the water is in terms of the molar number of H2O.

[0025] Optionally, in the gel mixture II, TiO2: SiO2 = 0.02-0.05.

[0026] In the gel mixture II, R: SiO2 = 0.02-0.15.

[0027] In the gel mixture II, H2O: SiO2 = 12-20.

[0028] In the gel mixture II, S: TiO2 = 6-18.

[0029] Optionally, the gel mixture II in step S2 is obtained by mixing an initial gel mixture B and an initial gel mixture C.

[0030] The initial gel mixture B is obtained by mixing a silicon source, an alkali source R and water; and the molar ratio of the components in the initial gel mixture B is:

[0031] R: SiO2 = 0-0.10: 1, preferably 0.02-0.15.

[0032] ​H2O:SiO2=6-30:1, preferably 12-20;

[0033] The initial gel mixture C is obtained by mixing a titanium source and a protective agent S; the molar ratio of the components in the initial gel mixture C is:

[0034] S:TiO2=4-20:1, preferably 6-18;

[0035] wherein the molar number of the silicon source is in terms of the molar number of SiO2, the molar number of the titanium source is in terms of the molar number of TiO2, the molar number of the alkali source R is in terms of the molar number of R, the protective agent S is in terms of the molar number of S, and the water is in terms of the molar number of H2O.

[0036] Optionally, in the initial gel mixture B, the molar ratio of R:SiO2is selected from any value or a range value between any two values selected from 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.10.

[0037] In the initial gel mixture B, the molar ratio of H2O:SiO2is selected from any value or a range value between any two values selected from 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30.

[0038] Optionally, in the initial gel mixture C, the molar ratio of S:TiO2is selected from any value or a range value between any two values selected from 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20.

[0039] Optionally, the structure formula of the quaternary ammonium base template agent is Formula I:

[0040]

[0041] wherein R 1 , R 2 , R 3 , R 4 are each independently selected from any one of C1-C4 alkyl, R 1 , R 2 , R 3 and R 4 are the same or different.

[0042] Optionally, the quaternary ammonium base template agent is selected from tetrapropylammonium hydroxide (TPAOH).

[0043] Optionally, in step S2, the initial gel mixture C is added dropwise into the initial gel mixture B under stirring to obtain the gel mixture II.

[0044] Optionally, in step S3, the product after the heating crystallization II is separated, washed and dried to obtain the nano-flake-like hierarchical pore TS-1 molecular sieve.

[0045] Optionally, in step S3, the molar content of SiO2 in the crystal seed solution I is 3-10% of the molar content of SiO2 in the gel mixture II.

[0046] Optionally, in step S3, the molar content of SiO2 in the crystal seed solution I is selected from any value or a range between any two values selected from 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% of the molar content of SiO2 in the gel mixture II.

[0047] Optionally, in step S1, the crystallization I is dynamic crystallization.

[0048] Optionally, in step S1, the temperature of the crystallization I is 60-140°C, and the time of the crystallization I is 0.5-24h; preferably 80-120°C, 2-16h; further preferably the crystallization temperature is 60-120°C, and the crystallization time is 8-24h; further preferably the crystallization temperature is 60-115°C, and the crystallization time is 9-24h.

[0049] Optionally, in step S1, the temperature of the crystallization I is selected from any value or a range between any two values selected from 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, and the time of the crystallization I is selected from any value or a range between any two values selected from 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24h.

[0050] Optionally, in step S3, the temperature of the crystallization II is 140-220°C, and the time of the crystallization II is 0.5-48h. Preferably, the temperature of the crystallization II is 160-220°C, and the time of the crystallization II is 1-12h.

[0051] Optionally, in step S3, the temperature of the crystallization II is selected from any value or a range between any two values selected from 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C.

[0052] Optionally, the silicon source in the initial gel mixture A is selected from at least one of silica sol, tetramethyl orthosilicate and tetraethyl orthosilicate.

[0053] Optionally, the silicon source in the gel mixture II is selected from at least one of silica sol, silica gel, chromatographic column silica gel, tetramethyl orthosilicate, tetraethyl orthosilicate and white carbon black.

[0054] Optionally, the titanium source is selected from at least one of tetraethyl titanate, tetra-n-butyl titanate, titanium tetrachloride, titanium sulfate and titanium isopropyl alcohol.

[0055] Optionally, the protective agent S is selected from at least one of ethanol, isopropyl alcohol, acetylacetone, acetic acid and triethanolamine.

[0056] Optionally, the base source R in the gel mixture II is selected from a compound having the structure of formula II:

[0057]

[0058] In formula II, R1, R2, R3 are each independently selected from H or an alkyl group having a carbon atom number of 1-4.

[0059] Optionally, the base source R is selected from at least one of ammonia, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, n-propylamine, di-n-propylamine, tri-n-propylamine, isopropylamine, diisopropylamine, triisopropylamine, n-butylamine, di-n-butylamine, tri-n-butylamine.

[0060] Optionally, in step S1, the solid in the crystal seed solution I has an amorphous structure, which is shown by XRD as amorphous, and the particle size is 10-20 nm, and the particle structure contains a five-membered ring structure.

[0061] Optionally, in step S3, the titanium silicalite TS-1 is calcined in air at a temperature of 400-600°C.

[0062] Optionally, in step S3, the calcination temperature is selected from any value or a range value between any two values of 400°C, 420°C, 450°C, 470°C, 190°C, 500°C, 520°C, 550°C, 580°C, 600°C.

[0063] In a second aspect, the present application provides a titanium silicalite TS-1 synthesized by the above synthesis method.

[0064] Optionally, the titanium silicalite TS-1 has a microporous and mesoporous multi-level pore structure.

[0065] Optionally, the pore size of the mesopore is 5-50 nm, and the volume of the mesopore is 0.25-0.43 cm 3 g -1 .

[0066] Optionally, the pore size of the mesopore is 10-40 nm.

[0067] Optionally, the pore size of the mesopore is 20-30 nm.

[0068] Optionally, the titanium silicalite TS-1 has MFI topology structure, and Ti species therein has tetrahedral structure.

[0069] Optionally, the pore size of the mesopore is 5-50 nm, and the volume of the mesopore is 0.25-0.43 cm 3 g -1 .

[0070] Optionally, the titanium silicalite TS-1 has nanosheet morphology, and the length, width and thickness thereof are 200-300 nm, 150-250 nm and 40-60 nm, respectively.

[0071] In the present application, the "silicon-titanium ratio" refers to the molar ratio of silicon element to titanium element.

[0072] Compared with the prior art, the present application has the following beneficial effects:

[0073] (1) The synthesis method provided by the present application, under the assistance of high-activity crystal embryo solution, does not introduce mesopore or macropore template agent, and only a small amount of micropore template agent (only 1 / 10-1 / 20 of the template agent of the conventional method) is used, so that the titanium silicalite with micropore, mesopore and macropore multi-pore structure can be synthesized.

[0074] (2) The product obtained by the synthesis method provided by the present application has single Ti coordination, high skeleton Ti content, and the product yield is as high as about 92%.

[0075] (3) The method provided by the present application does not use mesopore template agent and does not use complicated post-processing technology, so that the synthesis cost is lower, the crystallization time is greatly reduced, the production efficiency is improved, the production energy consumption is reduced, and the large-scale production of titanium silicalite is facilitated. BRIEF DESCRIPTION OF DRAWINGS

[0076] Figure 1 X-ray diffraction pattern of the crystal embryo powder 1# provided for Example 1 of the present application;

[0077] Figure 2 Infrared spectrum of the crystal embryo powder 1# provided for Example 1 of the present application;

[0078] Figure 3 X-ray diffraction pattern of the sample 1# provided for Example 1 of the present application;

[0079] Figure 4 Transmission electron microscope picture of the sample 1# provided for Example 1 of the present application;

[0080] Figure 5 UV diffuse reflectance spectrum of sample 1# provided for Example 1 of the present application;

[0081] Figure 6 Physical adsorption spectrum of sample 1# provided for Example 1 of the present application;

[0082] Figure 7 Pore size distribution graph of sample 1# provided for Example 1 of the present application;

[0083] Figure 8 X-ray diffraction spectrum of crystal embryo powder comparative sample 1# provided for Comparative Example 1 of the present application;

[0084] Figure 9 UV diffuse reflectance spectrum of comparative sample 1# provided for Comparative Example 1 of the present application. DETAILED DESCRIPTION

[0085] The present application will be further described below in connection with specific examples. The following description is merely exemplary of the application and is in no way intended to limit the same, as described above, the present application is disclosed in the preferred embodiments, however, not intended to limit the present application, any skilled in the art, within the scope of the technical solutions of the present application, using the above-mentioned disclosed technical content to make some changes or modifications are equivalent to equivalent embodiments, all belong to the scope of the technical solutions.

[0086] Unless otherwise specified, the raw materials and reagents used in the present application are commercially available and are used directly without treatment. The instruments and equipment used are based on the recommended protocols and parameters provided by the manufacturers.

[0087] The analysis methods in the examples of the present application are as follows:

[0088] X-ray powder diffraction phase analysis (XRD) was performed using an X'Pert PRO X-ray diffractometer from PANalytical, Netherlands, Cu target, Kα radiation source (λ = 0.15418 nm), voltage 40 KV, current 40 mA.

[0089] Elemental composition was determined using a Magix 2424X ray fluorescence analyzer (XRF) from Philips.

[0090] Low-temperature nitrogen physical adsorption was used to characterize the pore structure of the sample. The instrument used was an ASAP2020 physical adsorption instrument from Micromeritics. The specific surface area was calculated using the BET formula, and the pore distribution was calculated using the BJH formula.

[0091] The yield of the sample was calculated according to the following formula:

[0092] Yield = (mass of sample after calcination) ÷ (mass of SiO2 in mixture III + mass of TiO2) x 100%.

[0093] Example 1 Sample 1 # Synthesis of

[0094] A homogeneous mixture solution I was prepared by using silica sol as silica source, tetrapropylammonium hydroxide as microporous template agent, and the molar ratio of 1 SiO2: 0.3 TPAOH: 15 H2O. Then the mixture solution I was put into a synthesis kettle with a polytetrafluoroethylene liner and crystallized at 100°C for 6h to obtain a homogeneous crystal embryo solution I. A part of the crystal embryo solution was neutralized by acetic acid in stoichiometric ratio to obtain a solid powder, and the powder was dried and calcined to obtain a crystal embryo powder 1#.

[0095] A homogeneous mixture solution II was prepared by using tetramethyl orthosilicate as silica source, tetrabutyl titanate as titanium source, trimethylamine as alkali source, and anhydrous ethanol as protective agent. Then a part of the crystal embryo solution I was added into the mixture solution II, wherein the SiO2 content in the crystal embryo solution I accounted for 10% of the SiO2 content in the mixture solution II, to form a final mixture solution. The mixture solution was put into a synthesis kettle with a polytetrafluoroethylene liner and crystallized at 170°C for 4h to obtain a titanium silicalite molecular sieve. The product was centrifuged, washed, dried, and calcined to obtain a final molecular sieve product. The XRF result showed that the Si / Ti of the product was 36.7, which was recorded as sample 1#.

[0096] Preparation of Example 2 Samples 2#-19#

[0097] Sample 2 # - 19 # The types and ratios of raw materials and the crystallization conditions of samples 2-19 are shown in Table 1. The preparation process was the same as that of sample 1 in Example 1. #

[0098] Table 1. Synthesis and crystallization conditions of molecular sieves in Examples 1-19

[0099]

[0100]

[0101] Example 20 Sample 1 # - 19 # XRD and IR analysis of the crystal embryo solution containing solids

[0102] The XRD of the crystal embryo powder corresponding to the crystal embryo solution prepared in the examples was amorphous, but the infrared IR characterization contained a large number of characteristic peaks that could be attributed to the 5-membered ring structure consistent with the position of MFI zeolite, typical representatives were as follows: Figure 1 ​The XRD pattern of preform powder 1# shows that the preform powder has an amorphous structure. The XRD patterns of preform powders 2#-19# are similar to those of preform powder 1#. Figure 1 The proximity indicates that both are amorphous structures; Figure 2 The IR spectrum of the preform powder #1 shows that at 550 cm⁻¹... -1 There are characteristic peaks nearby that can be attributed to a 5-membered ring structure. The IR spectra of the preform powder 2#-19# are similar to those of the preform powder. Figure 2 Approximately 550cm -1 Vibrational peaks consistent with those of MFI-structured zeolites can be observed in the vicinity, indicating that the synthesized embryo contains a large number of zeolite structural units.

[0103] Example 21

[0104] Sample 1 # ~19 # XRD, SEM, UV-Vis, N2 physisorption and pore size distribution analysis

[0105] Sample 1 was examined using X-ray diffraction, scanning electron microscopy, and ultraviolet diffuse reflectance. # ~19 # Perform the analysis.

[0106] Sample 1 prepared in the example # ~19 # All are high-purity and highly crystallinity TS-1 molecular sieves with MFI topology, typical examples include... Figure 3 Medium sample 1 # XRD pattern of sample 2. # ~19 # The XRD patterns of sample 1 show that the peak positions and shapes are basically the same, and the relative peak intensities fluctuate within ±5% depending on the synthesis conditions, indicating that sample 1 # ~19 # It exhibits the characteristics of an MFI structure and is free of impurities; Sample 1 # ~19 # All of them have a nanosheet-like morphology, with typical examples being... Figure 4 The SEM image of sample 1 shows that the product has a sheet-like structure with dimensions of approximately 200nm*150nm*50nm. The portion containing the 10-membered ring has a dimension of only about 50nm along the b-axis. The particle size is relatively uniform. Sample 2... # ~19 # The SEM image results show that the product morphology and particle size are related to Figure 1 Sample 1# has similar dimensions; Sample 1 # ~19 # All Ti species exist as Ti species with a four-coordinated skeleton, a typical example being... Figure 5The UV-Vis graph of sample 1# can show that the Ti in the product mainly exists in the form of four-coordinated (210-220 nm), and there is almost no non-framework Ti (230-270 nm) and nano TiO2 (310-330 nm); the UV-Vis graph of sample 2 # ~19 # is similar to that of sample 1#, and the product mainly exists in the form of four-coordinated species, and there is no non-framework Ti and TiO2 species. Figure 6 and Figure 7 are respectively the physical adsorption curve and the pore size distribution graph of the product, which can show that, under the premise of ensuring the micropore volume of the product, the mesopore volume of the product reaches 0.32 cm 3 g -1 , and the mesopore size distribution is between 10-30 nm; the physical adsorption curve and the pore size distribution of sample 2 # ~19 # are respectively similar to Figure 6 and Figure 7 , so it can be seen that the product obtained by the scheme has high framework Ti content and multi-level pore structure, and the product yield can reach 92%.

[0107] Comparative sample 1 # Preparation of comparative sample 1

[0108] The specific ingredient ratio, ingredient process and crystallization conditions are the same as those in the preparation of sample 1 # of example 1, except that the crystallization time of the crystal embryo solution I is extended to 48 h, and the solid powder obtained by neutralizing the crystal embryo solution with acetic acid in a stoichiometric ratio is dried and calcined, and the obtained sample is recorded as crystal embryo powder comparative sample 1#. The crystal embryo solution synthesized by comparative example 1 is used to synthesize the final sample, which is recorded as comparative sample 1#.

[0109] UV-Vis analysis of comparative sample 1#

[0110] The XRD, SEM and physical adsorption results (not given) of comparative sample 1# are similar to the corresponding results of sample 1#, but its UV-Vis is as shown in Figure 9 , comparative sample 1# contains a large amount of non-framework Ti species (230-270 cm -1 ). It can be seen that the pre-crystallization seed solution is not conducive to the entry of Ti species into the framework during the induction synthesis, so it is crucial to strictly control the aging conditions of the crystal embryo solution and avoid excessive crystallization.

[0111] The main reason for the amorphous crystal embryo in the present application is to control the aging time and aging temperature.

[0112] Compared with the crystal seed, the crystal embryo solution of the present application has a significantly smaller crystal grain size, and the Ti species is four-coordinated and does not contain non-framework Ti.

[0113] If the crystal embryo solution of the present application is excessively crystallized to form a product with partial crystal structure, although the morphology of the final product is not much different, the Ti coordination is obviously different. If a conventional crystal seed is selected, not only the Ti coordination is not good, but the particle size is also significantly increased.

[0114] The above is only a few embodiments of the present application, and does not limit the present application in any form. Although the preferred embodiments are disclosed above, they are not intended to limit the present application. Any skilled person in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, which are equivalent to equivalent embodiments and belong to the scope of the technical solution.

Claims

1. A method for synthesizing titanium-silicon molecular sieve TS-1, characterized in that, The method includes the following steps: S1: Raw materials containing silicon source, quaternary ammonium base template agent and water are mixed to obtain initial gel mixture A. The initial gel mixture A is heated and crystallized I under closed conditions to obtain preform solution I. The solid in the preform solution I has an amorphous structure. S2: Raw materials containing silicon source, alkali source R, water, titanium source and protective agent S are mixed to obtain gel mixture II; S3: The preform solution I in step S1 and the gel mixture II in step S2 are mixed to obtain gel mixture III. The gel mixture III is heated and crystallized under sealed conditions to obtain the titanium silicon molecular sieve TS-1.

2. The method for synthesizing titanium-silicon molecular sieve TS-1 according to claim 1, characterized in that, In step S1, the solid particles in the preform solution I have a size of 10 to 20 nm and contain a five-membered ring structure.

3. The method for synthesizing titanium-silicon molecular sieve TS-1 according to claim 1, characterized in that, In step S1, the molar ratio of the silicon source, the quaternary ammonium base template agent, and the water in the initial gel mixture A is: Template agent: SiO2 = 0.10 ~ 0.50:1; H2O:SiO2 = 4 ~ 20:1; Wherein, the number of moles of the silicon source is calculated as the number of moles of SiO2, the number of moles of the template agent is calculated as the number of moles of quaternary ammonium base, and the number of moles of water is calculated as the number of moles of H2O.

4. The method for synthesizing titanium-silicon molecular sieve TS-1 according to claim 1, characterized in that, In step S2, the molar ratio of the silicon source, the titanium source, the alkali source R, the protective agent S, and the water in the gel mixture II is: SiO2: TiO2: R: S: H2O = 1: (0.02 ~ 0.10): (0.01 ~ 0.20): (0.04 ~ 0.2): (6 ~ 30); Wherein, the number of moles of the silicon source is calculated as the number of moles of SiO2, the number of moles of the titanium source is calculated as the number of moles of TiO2, the number of moles of R is calculated as the number of moles of the alkali source R, the number of S is calculated as the number of moles of the protective agent S, and the number of moles of water is calculated as the number of moles of H2O.

5. The method for synthesizing titanium-silicon molecular sieve TS-1 according to claim 1, characterized in that, The structural formula of the quaternary ammonium base template agent is Formula I: Formula I; Wherein, R in formula I 1 R 2 R 3 R 4 Each is independently selected from any of the C1-C4 alkyl groups, R 1 R 2 R 3 and R 4 Same or different.

6. The method for synthesizing titanium-silicon molecular sieve TS-1 according to claim 1, characterized in that, The quaternary ammonium base template agent is selected from tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.

7. The method for synthesizing titanium-silicon molecular sieve TS-1 according to claim 1, characterized in that, The gel mixture II in step S2 is obtained by mixing the initial gel mixture B and the initial gel mixture C; The initial gel mixture B is obtained by mixing a silicon source, an alkali source R, and water; the molar ratio of each component in the initial gel mixture B is: R:SiO2 = 0 ~ 0.10:1; H2O:SiO2 = 6~30:1; The initial gel mixture C is obtained by mixing a titanium source and a protective agent S; the molar ratio of each component in the initial gel mixture C is: S:TiO2 = 4 ~ 20:1; Wherein, the number of moles of the silicon source is calculated as the number of moles of SiO2, the number of moles of the titanium source is calculated as the number of moles of TiO2, the number of moles of the alkali source R is calculated as the number of moles of R, the number of moles of the protective agent S is calculated as the number of moles of S, and the number of moles of water is calculated as the number of moles of H2O.

8. The method for synthesizing titanium-silicon molecular sieve TS-1 according to claim 1, characterized in that, In step S3, the molar content of SiO2 in the preform solution I is 3 to 10% of the molar content of SiO2 in the gel mixture II.

9. The method for synthesizing titanium-silicon molecular sieve TS-1 according to claim 1, characterized in that, In step S1, the temperature of crystallization I is 60~140℃, and the time of crystallization I is 0.5~24h.

10. The method for synthesizing titanium-silicon molecular sieve TS-1 according to claim 1, characterized in that, In step S3, the temperature of crystallization II is 140~220℃, and the time of crystallization II is 0.5~48h.

11. The method for synthesizing titanium-silicon molecular sieve TS-1 according to claim 1, characterized in that, The silicon source in the initial gel mixture A is selected from at least one of silica sol, methyl orthosilicate, and ethyl orthosilicate.

12. The method for synthesizing titanium-silicon molecular sieve TS-1 according to claim 1, characterized in that, The silicon source in the gel mixture II is selected from at least one of silica sol, silica gel, silica gel for chromatography, methyl orthosilicate, ethyl orthosilicate, and silica fume. The titanium source is selected from at least one of tetraethyl titanate, tetrabutyl titanate, titanium tetrachloride, titanium sulfate, and titanium isopropoxide. The protective agent S is selected from at least one of ethanol, isopropanol, acetylacetone, acetic acid, and triethanolamine.

13. The method for synthesizing titanium-silicon molecular sieve TS-1 according to claim 1, characterized in that, The alkali source R in the gel mixture II is selected from compounds having the structure of formula II: Formula II; In Formula II, R1, R2, and R3 are each independently selected from H or an alkyl group having 1 to 4 carbon atoms.

14. The method for synthesizing titanium-silicon molecular sieve TS-1 according to claim 1, characterized in that, The alkali source R in the gel mixture II is selected from at least one of ammonia, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, n-propylamine, di-n-propylamine, tri-n-propylamine, isopropylamine, diisopropylamine, triisopropylamine, n-butylamine, di-n-butylamine, and tri-n-butylamine.

15. The method for synthesizing titanium-silicon molecular sieve TS-1 according to claim 1, characterized in that, In step S3, the titanium-silicon molecular sieve TS-1 is calcined in air at a temperature of 400~600℃.

16. A titanium-silicon molecular sieve TS-1, characterized in that, It is synthesized by the synthesis method of titanium-silicon molecular sieve TS-1 as described in any one of claims 1 to 15.

17. The titanium-silicon molecular sieve TS-1 according to claim 16, characterized in that, The titanium-silicon molecular sieve TS-1 has a multi-level pore structure consisting of micropores and mesopores.

18. The titanium-silicon molecular sieve TS-1 according to claim 16, characterized in that, The titanium-silicon molecular sieve TS-1 has an MFI topology, in which the Ti species have a four-coordinate structure; the mesopores have a pore size of 5 nm to 50 nm and a volume of 0.25 to 0.43 cm³. 3 g -1 The titanium-silicon molecular sieve TS-1 has a nanosheet-like morphology, with a length, width and thickness of 200 ~ 300 nm, 150 ~ 250 nm and 40 ~ 60 nm, respectively.

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